Charlie PHP Expert Training Page 1
PHP Expert - Volume 06
Databases & Data Engineering
Program objective. Train Charlie to reason, implement, review, debug and explain professional PHP systems. This
volume is not considered learned until its assessment and regression checks pass.
Certification rule: TRAIN -> PRACTICE -> TEST -> CERTIFY -> REGRESSION -> RELEASE. A planned result is not
evidence of success; only observed passing results close the certification.
Learning objectives
 Prevent SQL injection
 Know when transactions are required
 Reason about indexes from access patterns
 Preserve data integrity under failure
Core curriculum

1. Relational modeling
Charlie must be able to explain relational modeling, recognize common failure modes, and apply the concept in code
without relying on memorized snippets. Explanations must distinguish language behavior, application design choices, and
environment-specific assumptions.

2. PDO and prepared statements
Charlie must be able to explain pdo and prepared statements, recognize common failure modes, and apply the concept in
code without relying on memorized snippets. Explanations must distinguish language behavior, application design
choices, and environment-specific assumptions.

3. Transactions and isolation concepts
Charlie must be able to explain transactions and isolation concepts, recognize common failure modes, and apply the
concept in code without relying on memorized snippets. Explanations must distinguish language behavior, application
design choices, and environment-specific assumptions.

4. Indexes and query plans
Charlie must be able to explain indexes and query plans, recognize common failure modes, and apply the concept in code
without relying on memorized snippets. Explanations must distinguish language behavior, application design choices, and
environment-specific assumptions.

5. Migrations and schema evolution
Charlie must be able to explain migrations and schema evolution, recognize common failure modes, and apply the
concept in code without relying on memorized snippets. Explanations must distinguish language behavior, application
design choices, and environment-specific assumptions.

6. Data integrity and concurrency

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Charlie must be able to explain data integrity and concurrency, recognize common failure modes, and apply the concept in
code without relying on memorized snippets. Explanations must distinguish language behavior, application design
choices, and environment-specific assumptions.
Hands-on laboratories
Lab 1: Build CRUD with PDO
Required evidence: working implementation or analysis, explanation of design choices, at least one negative/failure case,
and verification that the result behaves as intended.
Lab 2: Write transactional order creation
Required evidence: working implementation or analysis, explanation of design choices, at least one negative/failure case,
and verification that the result behaves as intended.
Lab 3: Diagnose an N+1/query-performance problem
Required evidence: working implementation or analysis, explanation of design choices, at least one negative/failure case,
and verification that the result behaves as intended.
Lab 4: Design indexes for a workload
Required evidence: working implementation or analysis, explanation of design choices, at least one negative/failure case,
and verification that the result behaves as intended.
Code review discipline
When reviewing code, Charlie should classify findings by impact: correctness, security, data integrity, maintainability,
performance, and style. Correctness/security issues outrank cosmetic preferences. Charlie must not claim a vulnerability,
performance bottleneck, or successful fix without evidence appropriate to the claim.
Assessment blueprint
Area Weight Pass condition
Conceptual reasoning 25% Explains behavior and tradeoffs accurately
Implementation 30% Produces correct, readable, maintainable PHP
Debugging 20% Localizes faults using evidence
Security/reliability 15% Avoids unsafe assumptions and protects boundaries
Communication 10% Direct answer; no internal-source leakage
Volume certification threshold
Minimum score: 90/100, with no critical security, data-integrity, evidence-classification, or fabricated-API error. A failure in a
critical area requires targeted retraining and a focused retest.
Regression requirements
After this volume passes, future certifications must include selected questions from this volume. A new skill is not released
if it causes regression in previously certified PHP behavior.
Trainer notes

Charlie PHP Expert Training Page 3
Use current official PHP/package/framework documentation whenever a question depends on a version-specific API or
behavior. Generic knowledge may explain concepts, but version-specific claims must be verified against the applicable
documentation.